Enchanced energy absorbing materials

ABSTRACT

Dense, highly stable, high performance ballistic material comprises at least one woven layer of ballistic grade fiber (preferably a stack of such layers) and at least one nonwoven layer of fabric which is entangled with the woven or unidirectional layer by needle felting. The resulting core material does not require assembly of individual woven layers during subsequent manufacture of ballistic articles and exhibits excellent ballistic performance at low areal densities and thicknesses.

[0001] This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/409,225, filed Sep. 10,2002 and herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to enhanced energy absorbing materials andmethods of making them. The materials have utility in the manufacture ofballistic vests, hard and soft armor, life protective systems, andanti-ballistic systems.

[0004] 2. Description of the Prior Art

[0005] Materials made from ballistic grade fibers are known in the art,such as the well known aramid fiber-based material sold under thetradename Kevlar®. Methods of processing these materials into finishedarticles are also known. Ballistic fiber materials, ballistic vestconstructions and other materials and methods are described, forexample, in U.S. Pat. Nos. 6,276,255; 6,268,301; 6,266,819; 6,248,676;and 6,026,509, which are incorporated by reference. The materials andmethods described in these United States Patents may be used, withoutlimitation, in combination with the novel aspects of the inventiondescribed herein.

[0006] Needle felting, sometimes referred to herein as needle punchingor simply needling, is a process used in the textile industry in whichan element such as a barbed needle is passed into and out of a fabric toentangle the fibers. Needle felting itself is not new, and is describedfor example in U.S. Pat. Nos. 5,989,375; 5,388,320; 5,323,523;3,829,939; and 6,405,417, all of which are incorporated by referenceherein.

[0007] The use of quasi-unidirectional fabric layers in ballisticmaterials is known. For example, a quasi-unidirectional fabric iscommercially available from Barrday Inc. of Cambridge Ontario, Canadaunder the trade name Sentinel®. This fabric comprises at least twounidirectional fabric layers cross-laid in a 0/90 configuration relativeto each other. These ballistic resistant yarns are woven into a secondfabric composed of yarns having substantially lower tenacity and tensilemodulus than the ballistic cross-laid yarns to hold the ballistic yarnsin place. This method of construction, in theory, forms a fabricsubstantially stronger than conventional woven materials due to the lackof bending in the ballistic resistant yarns that results from atraditional weaving operation. However, there is a limitation in theperformance of such materials due to the inherent lack of stability inthe structure. Because the ballistic yarns are not secured in positionduring a ballistic event, they will spread and allow passage through theinterstices by a projectile.

[0008] Thus, there continues to be a need for fabrics with highballistic resistant performance in a dense, compact format which can beconveniently manufactured.

SUMMARY OF THE INVENTION

[0009] In one aspect, the invention is a ballistic material comprisingat least one woven layer of ballistic grade fiber and at least onenonwoven layer of fabric, said nonwoven layer entangled with the wovenlayer in a direction substantially perpendicular to an x-y plane of theballistic material, preferably by a needle felting process. As usedherein, “woven” includes unidirectional and quasi-unidirectionalfabrics.

[0010] The invention may be embodied as a stack of woven layers (such asthe quasi-unidirectional Sentinel® fabric mentioned above) and anonwoven layer which is attached to and entangled with the stack ofwoven layers on one or both faces to form an integral structure havingan areal density of about 0.07 pounds per square foot (342 g/m²) toabout 10 pounds per square foot (48.8 kg/m²). The resulting integralstructure offers advantages in handling and subsequent manufacturingbecause the material is ready-to-use and does not require assembly ofindividual ballistic fabric layers.

[0011] In another aspect, the invention is a method of making aballistic material which comprises the steps of superposing a nonwovenfiber layer on a ballistic grade woven fiber layer or layers to form astack, and subjecting the stack to needle felting until the fiber layersare attached and fibers of the nonwoven layer are entangled ininterstices of the woven layer or layers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is an exploded view of a ballistic material showingnonwoven layers, layers of ballistic grade material, and a graphicalrepresentation of the needle felting elements.

[0013]FIG. 2 is a graph showing the performance of ballistic materialsaccording to the invention compared to prior art ballistic materials.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Referring to FIG. 1, ballistic material (4) according to theinvention extends generally in the x-y plane. At least one andpreferably a stack of layers (1) comprises ballistic grade wovenfabrics, such as layers of unidirectional fiber tows or yarns. Ifunidirectional tows or yarns are used, these are preferably cross-laidat 90 degree angles with respect to one another and held in place bylightly stitching, sewing or interweaving lightweight yarns such thatthe material remains manageable during the manufacturing processeswithout separating and without bending the individual tows or yarns.

[0015] In a unidirectional fabric the tows all run in the samedirection. In a quasi-unidirectional fabric the tows may be laid in morethan one direction. As used herein, “unidirectional” encompasses bothunidirectional and quasi-unidirectional fabric, unless the contextrequires otherwise.

[0016] Fabrics woven from ballistic fibers in a variety of weave stylesincluding plain, basket, twill, satin and other complex weavesincluding, but not limited to, unidirectional, quasi unidirectional, andthree dimensional materials, alone or in combination, can be used as thewoven layers. As used herein “woven” fabrics includes stitched tows andknits. A plurality of knitted layers or stitched tows may be used withthe invention.

[0017] In preferred embodiments, stack of layers (1) comprises multiplelayers of quasi-unidirectional fabric such as that commerciallyavailable from Barrday Inc. of Cambridge Ontario, Canada, under thetrade name Sentine®. This material is a fabric having unidirectionalballistic resistant yarns in at least two layers cross-laid at ninetydegree angles relative to each other. The ballistic resistant yarns arethen held in place by being woven in a second fabric composed of yarnshaving substantially lower tenacity and tensile modulus than theballistic cross-laid yarns. Alternatively, the layer(s) (1) may simplybe woven ballistic grade fibers such as Kevlar® (para-aramid fibers),poly (p-phenylene-2,6-benzobisoxazole) (PBO), Spectra® (high molecularweight polyethylene fibers) or ballistic nylons.

[0018] The ballistic grade layer(s) (1) is combined with nonwovenbatting layers (2) or sandwiched between layers of nonwoven battingmaterial. After aligning the material, the stack is subjected to aneedle felting process to attach the layers to each other, increase thedensity and stabilize the finished fabric.

[0019] In a preferred embodiment of the present invention, the nonwovenlayer is composed of a high performance ballistic resistant fiber,especially a ballistic resistant fiber having a tenacity of at least 15grams per denier (13.5 g/decitex) and a tensile modulus of at least 400grams per denier (360 g/decitex) (hereinafter “ballistic grade nonwovenfibers”). The nonwoven layer may be selected from natural fibers andsynthetic fibers. Natural fiber includes cotton, wool, sisal, linen,jute and silk. Synthetic fiber includes aramid fibers, extended chainpolyethylene fibers, PBO fibers, regenerated cellulose, rayon, polynosicrayon, cellulose esters, acrylics, modacrylic, polyamides, polyolefins,polyester, rubber, synthetic rubber, saran, glass, polyacrylonitrile,acrylonitrile-vinyl chloride copolymers, polyhexamethylene adipamide,polycaproamide, polyundecanoamide, polyethylene, polypropylene andpolyethylene terephthalate. It is possible to use non-ballistic gradenonwoven fibers for the nonwoven layer and still produce a materialhaving satisfactory ballistic performance for some applications.

[0020] The needle felting step stabilizes the fabric layers and preventsthe individual tows from separating. In a preferred embodiment, thenonwoven layer(s) (2) comprises ballistic grade staple fibers, and theneedle felting step entangles these fibers in the interstices of thewoven fabric or cross-laid tows or yarns so that some are in a directionsubstantially perpendicular to the x-y plane of the fabric andmechanically connects the fabric plies. This mechanical bond prevents ahigh-energy projectile from spreading the individual tows of theunidirectional fabric layers, as the projectile acts to penetrate thematerial. While entanglement of nonwoven fibers prevents tows fromseparating, the process also prevents delamination of the individuallayers. In addition, this stabilization process increases the density ofthe material, thereby engaging more fibers per unit volume. In preferredembodiments, a nonwoven layer is attached on one side of a stack offabric layers by needlefelting; however a ready-to-use ballisticmaterial according to the invention may have nonwoven layers attached onboth sides thereof.

[0021] The thickness of the finished material is not particularlylimited and may range from about 0.025 in. (0.0635 cm) to about 4.0 in.(10.06 cm), preferably from about 0.10 in. (0.254 cm) to about 2.0 in.(5.03 cm), depending on the end use and the desired number of wovenfabric layers. The number of woven fabric layers (includingunidirectional or quasi-unidirectional layers) in a stack is likewisedetermined by the type of woven layers used and the end use. More thantwo, for example four to five hundred, and preferably four to twentylayers of woven fabric attached to a nonwoven layer is appropriate toform a core material for many life protection systems applications. Inembodiments, a first stack having a plurality of woven layers and anonwoven layer on a face thereof is prepared by needle punching, and asecond stack having similar construction is prepared. The first stackand the second stack may be then needlepunched together so that thenonwoven layers face opposite sides of the material.

[0022] The needle felting of the nonwoven layer or layers and the stackof woven layers must be varied according to the woven fabric type. Thevariation of the needling process may include the amount of needlepunches per unit area and/or the depth of those punches. The optimalamount and type of needling, and the amount of nonwoven fiber can bedetermined by ballistic testing, preferably performed using standardballistic testing procedures, such as Military Standard (Mil Std) 662 For National Institute of Justice (NIJ) Standard 0104.04, which areherein incorporated by reference.

[0023] For example only and not by way of limitation, materialsaccording to the Examples herein were prepared by placing nonwovenmaterial (which may be manufactured, for example, by dry laid cardingand mechanical needling) having an areal weight of about 2.5 oz/sq.yd.(84.78 g/m²) and a thickness of about 0.060 in. (0.152 cm) at the inletside of a needlepunch loom on an automatic roll feed system timed tofeed the material at the same rate as the machine speed. Layers ofquasi-unidirectional woven materials were arranged in a stackconfiguration on the inlet side of the needlepunch loom. The leadingedge of the woven layers were then tacked together to a leader fabric (afabric used solely to bring another material through the needlepunchloom) for stability. The nonwoven fabric was fed to the needlepunch loomedge and the entire system of nonwoven and woven materials was fed intothe needlepunch loom for consolidation. The step of superposing anonwoven layer on a stack of woven layers includes placing a nonwovenlayer above the stack of woven layers on the loom. Layers of nonwovenfabric may be interleaved between layers of woven fabric.

[0024] The first pass through the needlepunch loom used 400penetration/sq.in. (62 penetrations/cm²) with an 8 mm penetration ofneedle into the materials. The type of needle used is a finishingneedle. The machine ran at 1.6 yards/minute (1.46 m/min.). Theconsolidated material is then run through the loom a second time withthe nonwoven component remaining face-up. The second pass is to ensurethat all of the woven layers are mechanically entangled in thez-direction with the nonwoven layer. The second pass through the loomwas at 600 penetrations/sq. inch (93 penetrations/cm²) with an 8 nmpenetration of needle into the materials. For this pass, the machine ranat 2.0 yards/minute (1.83 m/min.).

[0025] As a result, the nonwoven layer was firmly attached to the wovenlayers and the finished material was ready for use in the manufacture ofballistic articles without requiring assembly of individual layers.

[0026] After needle felting, the material may be further consolidated bycalendering the needle felted stack through nip rolls. Calendering in anip roll further densifies the system and reduces the overall thicknessprofile of the material. Calendering is the process of applyingpressure, and sometimes heat, to a material for further densification.The density of a consolidated material is generally increased between 40to 55 percent and the thickness decreased by between 30 to 35 percent.The combined result of these steps is expected to increase theperformance of the system in terms of ballistic testing performed inaccordance with NIJ standards for projectile penetration, back facesignature, and against fragment simulating projectiles (FSP's). Thefinished material may further be enhanced by the application of a waterrepellant treatment, or other coating or treatment.

[0027] Methods of mechanical entanglement, other than needlepunching,can be used, such as hydroentanglement, the use of the water or airjets,and the like.

[0028] Due to increased ballistic performance of fabrics according tothe invention, less material can be used to achieve equivalent ballisticperformance making the end products lighter weight, more flexible andthus more comfortable as a ballistic garment. The process adheresindividual layers together through the entanglement process, whichincreases the interlaminar shear strength and communication betweenadjacent layers during a ballistic event. This effect allows energy froman impacting projectile to be more readily absorbed and evenlydistributed throughout the fabric layers.

[0029] The thickness and weight of the finished ballistic material varydepending on the amount of fibers used in the nonwoven layer, the degreeof needle felting, and the type and number of woven layers in the stack.The format of the product also depends on the intended end use. Inconventional ballistic vest apparel, the vest typically consists ofmultiple layers of woven ballistic grade materials that are thenstitched, and in some cases laminated to hold the layers in place. Thelayers, commonly known as a pack, are then covered with a more wearabledress cover material. In the present invention, the introduction of theinsertion of a preassembled core for the ballistic protective componentis new. The core is considered the base ballistic protection from whichthe remaining level of ballistic protection is built. Several cores maybe added, as well as other ballistic grade materials known in the art,to obtain the desired ballistic performance of the pack. For a ballisticvest, a core material may be made with a single layer of nonwovenmaterial attached by needlepunching to a stack of woven layers (which isdefined to include unidirectional and quasi-unidirectional layers) toform a material having a thickness in a range of about 0.1 in. (0.254cm) to about 0.3 in. (0.76 cm), typically about 0.25 in. (0.63 cm),which may be cut as a single layer to form a vest.

[0030] Generally, an important goal for ballistic materials(particularly wearable materials) is to increase ballistic performanceat lighter material weight. A suitable material weight for a coreballistic material is in a range of about 0.07 lbs/ft² (342 g/m²) toabout 10 lbs/ft² (48.8 kg/m²), and preferably about 0.18 lbs/ft² (878g/m²) to about 0.60 lbs/ft² (2.928 kg/m²). In the most preferredapplications, the core ballistic material has a weight of 0.18 lbs/ft²(878 g/m²) to about 0.321 bs/ft² (1.562 g/m²).

[0031] In addition to the performance benefit, the needling processforms a ballistic core material that does not require further assemblyof the layers. For example, if the fabric were used by a ballistic vestmanufacturer to create a ballistic vest, the manufacturer may cut a unitof material from a single roll of fabric that has been tested to meetspecific ballistic requirements. This method avoids the additional laborof cutting many layers of ballistic fabric, stacking, counting andquilting or stitching layers together. The core material is thus“ready-made” ballistic material, offering economic as well asperformance advantages in a single monolithic core material that canthen be used as a building block to create various constructions innumerous potential products for both hard and soft armor materials.

[0032] The core material made according to the invention has other usesapart from the manufacture of ballistic vests and other ballisticgarments. For example, the material may be resinated and used as hardarmor or hard composite armor, and in both hard and soft containmentstructures, bomb containment structures and mitigating panels. The corematerials comprising several prefabricated layers provides forease-of-use in many of these applications.

[0033] Conventionally, processing by secondary steps enhances the use offabric in vests, blankets, and composites, particularly for bulletresistant applications. During a ballistic event, energy is transferredin several directions: orthogonally to the flight of the projectilealong the yarns of the fabric layer and simultaneously longitudinally tothe path of the projectile into the pack. This longitudinal energytransfer occurs before the projectile penetrates the fabric layer. Thistransfer of energy into the pack plays a significant role in stoppingthe projectile The layers of fabric must be in intimate contact forefficient longitudinal energy transfer. Therefore, the fabric layers areconventionally processed to maintain this contact. The secondary step(s)are also used to stiffen the ballistic pack and/or to reduce or spreadthe energy (blunt trauma) that is transferred to the body during thestop of a ballistic threat. Fabric subjected to a ballistic event ispushed back into a cone shape by the projectile during impact. The conehas a larger surface area than the initial flat surface, and thesecondary processing permits the fabric to spread open in order to coverthe increased area. Such conventional secondary processing steps alsohelp to prevent the fabric layers from opening up during the ballisticevent. Conventional secondary steps that may be used include sewingand/or lamination of the fabric layers. The use of core technologyaccording to the invention replaces these conventional secondary stepsby increasing the intimate contact between the layers. In addition, thecore technology provides this contact in a more efficient manner. Themechanical entanglement of the core technology not only provides contactbetween fabric layers, but also increases contact between the towswithin each fabric layer. However, in some applications conventionalsecondary processes, including sewing and/or lamination, may be used incombination with mechanical entanglement.

[0034] Coatings known in the art, such as a water repellantpolytetrafluoroethylene coating, may advantageously be applied to thefinished fabric to improve the performance.

[0035] The following fabrics were prepared according to the invention:

EXAMPLE 1

[0036] A nonwoven fabric consisting of para-aramid fibers was superposedon eight cross-laid layers of a para-aramid quasi-unidirectional fabricto form a stack. The stack was subjected to needle felting consolidationto obtain a thickness of about 0.11 inches (0.28 cm) and a weight ofabout 0.24 lbs/sq. ft. (1.171 kg/m²). The resulting material exhibitedenhanced ballistic performance when compared to a stack of cross laidlayers of quasi-unidirectional fabric of comparable thickness, asdemonstrated in the Comparative Examples below.

EXAMPLE 2

[0037] A nonwoven fabric consisting of para-aramid fibers was superposedon eight layers of a para-aramid quasi-unidirectional fabric to form astack. The stack (prior to subsequent steps) had a cumulative thicknessof about 0.25 inches. The stack was subjected to needle feltingconsolidation. Subsequently seven additional woven layers(quasi-unidirectional) and a second nonwoven layer were simultaneouslyattached to the original stack via needling. The second nonwoven layerwas attached to the exposed woven side. Thus, the manufacture is similarto that of Example 1, except that a plurality of stacks of woven fabricand a plurality of nonwoven layers were used. The finished fabric had anareal density of about 0.48 lbs/sq. ft. (2.342 kg/m²), a thickness ofabout 0.2 in. (0.51 cm).

EXAMPLE 3

[0038] A nonwoven fabric consisting of para-aramid fibers was superposedon ten cross-laid layers of a para-aramid plain woven fabric to form astack The stack was subjected to needle felting consolidation. Thefinished material had a cumulative thickness of about 0.13 in. (0.33 cm)and a weight of about 0.38 lbs/sq. ft. (1.854 kg/m²). The core materialdesign of this Example is similar to that of Example 1 except that aplain weave woven layer was used.

EXAMPLE 4

[0039] A nonwoven fabric consisting of para-aramid fibers was superposedon ten cross-laid layers of a para-aramid plain woven fabric andconsolidated by needlepunching to form a first stack similar to thestack of Example 3. A second stack, substantially identical to the firststack, was attached back-to-back with the first stack so that the wovenlayers were sandwiched between the nonwoven layers. The finished fabrichad an areal density of about 0.76 lbs/sq. ft. (3.709 kg/m²) and athickness of about 0.24 in. (0.61 cm).

EXAMPLE 5

[0040] The fabric of Example 1 was further subjected to a calenderingstep between nip rolls, which carry the material between and through therolls and out the other side via the force of the rolls. The materialdensity was increased to 43 lb/ft³ (0.69 g/cm³) with a thickness of0.135 inches (0.34 cm), an increase in density of 50 percent, and adecrease in thickness of 33 percent.

COMPARATIVE EXAMPLES

[0041] A woven/nonwoven material configuration combined via mechanicalneedling according to the invention was compared to three standardballistic materials which were prepared using the same woven materialand different consolidation methods, for ballistic performance.Ballistic performance was measured using Mil Std 662. V-50, V-0 andcorresponding backface signature results were compared. V-50 is commonlyknown as the measurement of the velocity at which fifty-percent of theprojectiles fired penetrate the ballistic material under evaluation. V-0is commonly known as the measurement of the velocity at which zeropercent of the projectiles fired penetrate the ballistic material underevaluation. Backface signature measurements are determined by recordingthe depth at which the material penetrates into a clay backstop. NIJ hasdetermined that a backface signature of 44 mm or less is consideredsurvivable.

[0042] Comparative Example 1: An “x-stitch” was used to combineindividual layers of Sentinel® quasi-unidirectional woven fabric. Thetotal weight of the material was about 0.5 lbs/sq. ft. (2.44 kg/m²).

[0043] Comparative Example 2: A 1-inch quilt stitching was used tocombine individual layers of Sentinel® quasi-unidirectional wovenfabric. The total weight of the material was about 0.5 lbs/sq. ft. (2.44kg/m²). This quilted format is the typical design of conventionalballistic fabrics.

[0044] Comparative Example 3: Layers of Sentinel® quasi-unidirectionalwoven fabric were adhered to one another using a polymeric laminate.Heat was then applied to the total laminate structure to create thefinal consolidated material. This material is rigid and weighs 0.5lbs/sq. ft. (2.44 kg/m²).

[0045] Inventive Example: A needle punched nonwoven layer was used tocombine a stack of Sentinel® quasi-unidirectional woven fabric to obtaina total weight of about 0.5 lbs/sq. ft. (2.44 kg/m²). The core compoundswere formed using the method described in Example 1.

[0046] Table 1 lists the performance of Comparative Examples 1 through 3compared to the Inventive Example for both the V-50 value, in feet persecond, and the backface signature, in millimeters. The fabric accordingto the invention performs better than the Comparative Examples 1 through3 for both V-50 and backface signature. Although Comparative Example 2performs nearly the same for V-50, the quilt stitched material is morecumbersome to manufacture and has an unsatisfactory backface signature.Comparative Example 3 exhibited fair performance but Comparative Example3 is a rigid material that does not conform to the body. TABLE 1 ArealResults Density Pro- V-50 Backface Sample Stitching lbs/sq. ft. jectile(fps|m/s) (mm) Comp. Ex. 1 x-stitch 0.5 9 mm  990|302 70 Comp. Ex. 2 1inch quilt 0.5 9 mm 1241|378 52 Comp. Ex. 3 None 0.5 9 mm 1115|340 40Inventive None 0.5 9 mm 1264|385 34 Ex.

[0047] Table 2 shows the percentage improvement for the InventiveExample versus each of the Comparative Examples. TABLE 2 % ImprovementV50 Backface Comp. Ex. 1 28% 62% Comp. Ex. 2 27% 35% Comp. Ex. 3 12% 15%

[0048]FIG. 2 displays a graphical interpretation of the V-0 to V-50results for Comparative Examples 2 and 3 and the Inventive Example,showing the advantage of the needle punch consolidation versusconventional consolidation methods. The material incorporating needlingtechnology enhances and improves the ballistic performance as shown fromthe V-0 to V-50 data.

[0049] Generally the slope of the performance curve for traditionalwoven ballistic materials is shaped like an “S”. This is seen forComparative Example 2, which is a conventional ballistic materialdesign. Comparative Example 3, which is a rigid material, would not beexpected to have the S shaped profile. Depending on the type ofmaterial, the slope of the V-0 to V-50 curve can be gradual or steep. Agradual “S” shape makes the true and consistent V-0 value of a givendesign difficult to state accurately and is therefore less preferable.As shown in FIG. 2, the use of needling technology according to theinvention increases the slope of the curve, which allows a more accurateand reliable statement of V-0. This change in the slope also is anindication of the change in consistency of the materials used to buildthe technology. The slope of the curve for the needled materials showsan increased consistency in the overall material construction for theInventive Example.

[0050] The foregoing examples and detailed description are not to bedeemed limiting of the invention which is defined by the followingclaims. The invention is understood to encompass such obviousmodifications thereof as would be apparent to those of ordinary skill inthe art.

What is claimed is:
 1. A ballistic material comprising a stack of wovenlayers, and at least one nonwoven layer on a face of said stack of wovenlayers, said nonwoven layer attached to and entangled with the stack ofwoven layers by needlepunching to form an integral material having anareal weight of about 0.07 pounds per square foot (342 g/m²) to about 10pounds per square foot (48.8 kg/m²).
 2. The ballistic material of claim1, comprising a non woven layer on each face of said stack of wovenlayers.
 3. The ballistic material of claim 1, wherein the stack of wovenlayers comprises 4 to 20 quasi-unidirectional aramid fiber fabric layerscross laid at right angles.
 4. The ballistic material of claim 1,wherein the nonwoven layer consists essentially of fibers having atenacity of at least about 15 grams per denier (13.5 g/decitex) and atensile modulus of at least about 400 grams per denier (360 g/decitex).5. The ballistic material of claim 1, having a backface signature ofless than 44 mm at a material areal density of 0.5 pounds per squarefoot (2.44 kg/m²).
 6. The ballistic material of claim 1, calendered to athickness of about 0.1 inches (0.254 cm) to about 0.3 inches (0.76 cm)having an areal density of 0.18 pounds per square foot (878 g/m²) toabout 0.60 pounds per square foot (2.928 kg/m²).
 7. A ballistic materialcomprising at least one woven layer of ballistic grade fiber and atleast one nonwoven fiber layer, said nonwoven layer entangled with thewoven or unidirectional layer in a direction substantially perpendicularto an x-y plane of the ballistic material.
 8. The material of claim 7,wherein said nonwoven layer is entangled with the woven layer byneedlepunching.
 9. The material of claim 7, wherein said woven layercomprises unidirectional or quasi-unidirectional ballistic grade fibers.10. The material of claim 7, wherein said at least one nonwoven layercomprises ballistic grade fibers.
 11. The material of claim 7, whereinsaid at least one nonwoven layer comprises staple para-aramid fibers.12. The material of claim 7, comprising a plurality of layers ofunidirectional tows of ballistic grade fibers cross-laid at 90 degreeangles.
 13. The material of claim 7, comprising a plurality of layers ofwoven ballistic grade fabric.
 14. The material of claim 7, comprising aplurality of layers of knitted ballistic grade fabric.
 15. The materialof claim 7, comprising a plurality of layers of stitched tows ofballistic grade fibers.
 16. The material of claim 7, further comprisinga water repellent coating.
 17. The material of claim 7, having athickness reduced by calendering.
 18. A method of making a ballisticmaterial comprising the steps of: superposing at least one nonwovenfiber layer on a ballistic grade woven or unidirectional fiber layer toform a stack, and subjecting the stack to mechanical entanglement of thefibers of the nonwoven layer.
 19. The method of claim 18, wherein saidnonwoven layer is entangled with the woven layer by needlepunching. 20.The method of claim 18, wherein the stack comprises 4 to 500 layers ofunidirectional, quasi-unidirectional, knit, or stitched tow layers. 21.The method of claim 18, wherein the stack comprises 4 to 20 layers ofunidirectional or quasi-unidirectional aramid fiber fabric cross-laid atninety degree angles.
 22. The method of claim 21, wherein the stackcomprises nonwoven layers superposed and entangled on opposite sides ofsaid 4 to 20 layers of unidirectional or quasi-unidirectional aramidfiber fabric.
 23. The method of claim 16, further comprising a step ofcalendering the material after needle felting to increase the density.24. The method of claim 19, wherein the material is calendered to adensity of about 0.07 pounds per square foot (342 g/m²) to about 0.80pounds per square foot (3.906 kg/m²) and a thickness of about 0.1 inches(0.254 cm) to about 0.3 inches (0.76 cm).
 25. The method of claim 16,further comprising a step of applying a water-repellant coating on thematerial.
 26. The method of claim 16, comprising the step ofinterleaving nonwoven layers between layers of woven or unidirectionalfabric prior to needle felting.
 27. The method of claim 16, comprisingthe steps of needlepunching a first stack having a plurality of wovenlayers and a nonwoven layer on a face thereof, and needlepunching asecond stack having a plurality of woven layers and a nonwoven layer ona face thereof, and needle punching the first stack and the second stacktogether so that the nonwoven layers face opposite sides of thematerial.
 28. The method of claim 16, further comprising the step oftesting the ballistic material after manufacture for a backfacesignature of less than 44 mm, such that the material is ready-to-use inthe manufacture of ballistic articles.